Posted on 07/30/2007 5:38:23 PM PDT by roaddog727
“The whole Permian period, stretching from about 300 million to 250 million years ago, saw gradual warming. This would have slowed down circulation in the ocean, eventually leading to very low levels of oxygen in the water. Massive volcanism near the end of the Permian might have wreaked even further havoc on the environment.”
“I swear I didn’t leave my SUV idling, officer! Honest, I didn’t!”
Calling Inspector Legrasse ...
I was thinking oyster roast. :)
My favorite mollusks, right off the grill, hot and juicy with Tabasco and butter.
WOOHOO! Feeding my family and friends, and saving the world at the same time! I didn’t realizze I was such a hero!
The old shell game is apparently older than I thought.
So much for the “I’m doing my part to keep the mollusk pollution down” line.
Lawrence, and don’t forget the bubbles.
“If you go to the link, the title is now: “Mollusks provide clues to world’s worst die-off.” I don’t know if they changed it because readers complained, or because the author complained. The editors are always changing things and not always for the better.”
Perhaps it could also be due to the ridicule the article was receiving on our illustrious website as well......
:-)
I tried one once. It was a lot like picking someone else's nose.(Not that I've done that)
It tasted so vile that I spit it out.
urp
Clam up! ()
Trilobites were around before mollusks, had great eyelens, and came in a great variety of forms and sizes.
Much more interesting than most sendentary shellfish.
The Cambrian Period rules!!!
Well Zoidberg and his people did cause the extintion of anchovies.
True, but then along came the great Permian Extinction and...no more trilobites except index fossils for the Paleozoic. They vanished forever as living creatures. But they've sure been a big help to geologists!
bedout crater:Asteroid 'destroyed life 250m years ago'Earth's biggest mass extinction 251 million years ago was triggered by a collision with a comet or asteroid, US scientists say... In rock layers laid down at the time, there is a much higher concentration of complex carbon molecules called fullerenes that have different types, or isotopes, of helium and argon trapped inside them... The researchers believe these particular fullerenes are extraterrestrial because the gases trapped inside have an unusual ratio of isotopes that indicate they were made in the atmosphere of a star that exploded before our Sun was born. "These things form in carbon stars. That's what's exciting about finding fullerenes as a tracer," said Dr Luann Becker of the University of Washington, US. The telltale fullerenes were extracted from sites in Japan, China and Hungary, where the sedimentary layer at the boundary between the Permian and Triassic periods had been exposed... The research was made difficult because there are few 251-million-year-old rocks left on Earth. Most rocks of that age have been recycled through the planet's tectonic processes... The mass extinction of 251 million years ago was the greatest on record. Many fossils below the boundary, such as trilobites, which once numbered more than 15,000 species, are completely absent above it... It was thought that any asteroid or comet collision would leave strong evidence of the element iridium, the signal found in the sedimentary layer from the time of the dinosaur extinction. The team believes the difference might be because the two space bodies that slammed into Earth had different compositions... In 1996, Becker and Poreda discovered that fullerenes found in a huge impact crater in Canada came from space nearly two billion years ago. Last year, they showed that even more complex carbon molecules, with as many as 200 atoms, had survived from the impact that wiped out the dinosaurs.
by Dr David WhitehouseScientists Find Signs of Meteor Crash That Led to Extinctions in Era Before DinosaursScientists examining the layer of sediment corresponding to the die-offs discovered concentrations of the sturdy, soccer-ball-shaped carbon molecules, buckminsterfullerenes, or buckyballs. Within the buckyballs was a mix of helium and argon gases similar to that found in certain stars but unlike anything that could form naturally on Earth. A few inches below and above the extinction layer, they found very few buckyballs... Recent work indicates the extinctions happened quickly, within 100,000 years. That led to speculation that an asteroid or comet impact might be to blame... The buckyballs and gases were found in samples from Japan and China, while a sample from Hungary was almost devoid of buckyballs. Other scientists said that samples from other regions would be needed to confirm the findings and to rule out other potential sources, like cosmic dust... Dr. Robert J. Poreda, a professor of earth and environmental sciences at the University of Rochester and another author on the Science paper, said the energy released by the meteor, estimated at four to eight miles wide, would have been equivalent to a magnitude-12 earthquake... Dr. Becker, Dr. Poreda and their colleagues had previously found buckyballs at an impact crater in Sudbury, Canada, and in two meteorites. They have also found buckyballs containing similar types of gases in sediments dating from the dinosaur extinctions.
by Kenneth Chang
February 23, 2001Meteor May Have Started Dinosaur EraIn the layer of rock corresponding to the extinction, the scientists found elevated amounts of the rare element iridium. A precious metal belonging to the platinum group of elements, iridium is more abundant in meteorites than in rocks on Earth. A similar spike of iridium in 65 million-year-old rocks gave rise in the 1970's to the theory that a meteor caused the demise of the dinosaurs... The levels are only about one-tenth as high as those found at the later extinction. That could mean that the meteor was smaller or contained less iridium... In the same rock layer, Dr. Olsen and his colleagues found a high concentration of fern spores -- considered an indicator of a major disruption in the environment. Because spores carried by the wind can travel long distances, ferns are often the first plants to return to a devastated landscape. The scientists found more evidence of rapid extinction in a database of 10,000 muddy footprints turned to rock in former lake basins from Virginia to Nova Scotia... Because the sediment piles up quickly in lake basins, the researchers were able to assign a date to each footprint, based on the layer of rock where it was found. They determined that the mix of animals walking across what is now the East Coast of North America changed suddenly about 200 million years ago. The tracks of several major reptile groups continue almost up to the layer of rock marking the end of the Triassic geologic period 202 million years ago, then vanish in younger layers from the Jurassic period... Last year, researchers led by Dr. Ward reported that the types of carbon in rock changed abruptly at this time, indicating a sudden dying off of plants over less than 50,000 years. The footprint research reinforces the hypothesis that the extinction was sudden.
by Kenneth Chang
May 17, 2002Scientists Say Crater Is Result of a Killer MeteorA buried geological formation off the northwest coast of Australia, long thought to be remnants of an old volcano, is actually a 125-mile-wide crater formed by a devastating meteor strike 251 million years ago, scientists asserted yesterday. It was that meteor, they went on, that caused the largest mass extinction in the Earth's history... At the end of the Permian geological period and the start of the Triassic, 90 to 95 percent of the species in oceans died out, as did at least half of the backboned species on land... In 2001, Dr. Becker; Dr. Robert J. Poreda, a professor of earth and environmental sciences at the University of Rochester; and other scientists published a paper in Science that said they had found soccer-ball-shaped molecules known as buckyballs in sediments dating from the Permian-Triassic boundary. They said the buckyballs contained helium and argon that had an extraterrestrial chemical signature, suggesting they had come from a meteor. No one else has found buckyballs at the Permian-Triassic boundary. Dr. Becker said she knew of no one who had even looked.
by Kenneth Chang
May 14, 2004
Note: this topic is from . Thanks roaddog727.
Wow, ridiculous claim, I'd forgotten about this one.
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Note: this topic is from . Thanks roaddog727.
Changed my mind after 13 years, it's going into the GGG.
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